Classic cars forum & vehicle restoration.

[Mello]

I want to replace as many nuts and bolts etc on my car cas I can. It's a 1956 103E Ford Popular.

Does anybody know which bolt sizes were original? (Confused)

Thanks - Pete

[ukdave2002]

I don't know for sure, but most uk stuff designed before WW2 will use whitworth (BSW) & BSF and post war UNC& UNF.

The spanner size will give the game away, UNF/UNC are measured across the flats so 1/2" spanner will have a 1/2" gap, a 1/2" Whitworth spanner originaly fitted a Whitworth bolt with a shank/thread diameter of 1/2". The introduction of BSF (British Standard Fine) and BSW (British Standard Whitworth) in 1908 resulted in the head sizes being reduced by one step so the head size for the old Whitworth 1/4" bolt was used for the BSW/BSF 5/16" bolt, etc.

Also just to confuse you because whitworth and UNC have the same number of threads per inch (ie a 5/16 has 18 tpi ) the only difference being that whitworth has a 55 degree pitch and UNC 60 degree, they will fit each others threads quite easily! the nut or bolt head of course won't be the same size, so its quite common to find someone has fitted the wrong nut / bolt.

It may all sound a bit confusing, it gets worse if you have a Morris 8, as Morris used a french based engine that had metric threads, but to save the dealers having to buy new spanners they had all the metric thread nut & bolt heads made to fit Whitworth spanners

Cheers

Dave

[Mello]

Thanks Dave... lokks like UNF as I've been doing some spannering this morning and the bolts are mostly 1/2" or 9/16" or 7/16" (spanners) so that's pretty much what I expected.

Thanks for the info

[Nic Jarman]

I am replacing a lot of the bolts/nuts on my Morris 8 and I will be using UNF as once they are in and a coat of underseal over them no one will know the difference. Apart from everyone reading this thread.
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1936 Morris 8 Series 1
1973 MGB roadster
1977 MG Midget 1500
Dax Rush

[ukdave2002]

Nic, don't worry we wont tell!!!

[Jim.Walker]

Cars with American influence, such as Ford were the first British cars to use Unified Threads (AF spanner sizes) almost immediately after the 2nd World War. Many British Manufacturers continued with B.S.F. and Whitworth well into the 1950s.
NOT ALL UNC and Whitworth threads are the same pitch. From memory and without checking, that is limited to 1/4 5/16 and 3/8, though 3/16 may be.
Is it a good idea the change British threads to Unified? You cannot change studs etc. and that means carrying two sets of spanners! After all, BSF and Whitworth are still readily available (though the spanners are harder to find).
_________________
Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then!

[Richard H]

[ukdave2002]

Restoring the Morris I am using trying to stick with original BSW/BSF nuts and bolts, however they are getting ridiculously expensive , so may substitute some UNC/ F where practical. BSW / UNC thread pitches are the same up to at least an inch I think maybe be even 1.5 " .

Dave

[Austin-sixteen-Cornwall]

I am a bit worried by this talk of using UNC/F nuts & bolts on whit/BSF studs or threaded holes. If the application is critical say fixing cylinder head or Wheel nuts there may be a tendency for the thread to strip because the flanks of the thread will not be fully engaged, so I would council caution. I can buy Whit/BSF nuts locally at quite reasonable cost.

[ukdave2002]

[Phil - Nottingham]

I lost count after £200 spending on BSF nuts for my pre-war Rover 8 years . I would have spent half that if I had used UNF which are exactly same diameter but some of the head/nut sizes are slightly bigger although half were 1/4" which is 7/16" AF anyway and almost all the rest were 5/16" which does have a slightly bigger head than 1/2AF.

I doubt if anyone would notice!

I would never use UNF/metric on BSF studs or tapped holes though as even if pitch may almost the same the thread angle at 60º is not clse enough for my liking to the BSF angle of 55º

Similarly the even cheaper 6.8 & 10 mm mertric diameters arew not close enough for me particulary the 6mm vs the ¼UNF/BSF nearest equivalent - as teh haed at 10mm AF is far too small as well.

It is annoying to have use a mixture a spanner sizes as well - its very hadny to us ethe Whit/BSF spanners
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Rover P2
Rover P4
Rover P5 & P5B
Land Rover S2 & S3
Morris Mini Traveller Mk2

[Greg]

A very interesting Thread!!!!!

[Austin-sixteen-Cornwall]

I buy my nuts from :-
Duchy Fasteners, Units 1-4, Station Road Ind Est., Perranporth.
Tel: 01872 573999. Fax: 01872 573644.
I hope they can help you

[Keith D]

I think that this whole business of thread mixing is a case of "do it once and do it right!" The extra cost of the correct nuts/bolts/studs is a one off thing. Mixing threads means having to go through every spanner in your toolset to find which fits which nut! This is not a good option! I know; I was stupid enough to mix threads on a car in the past! Never again!
Keith

[George]

If anyone is interested I learned the formula for converting a Whitworth bolt to AF spanner size almost 50 years ago.

The formula is:-

1 1/2 d + 1/8"

Thus a Whitworth bolt diameter of 1/2" would yield an AF spanner size of 7/8"

That is one and a half times the diameter of the Whitworth bolt plus one eighth of an inch.

Likewise, a Whitworth bolt of 3/8" would be ( in AF terms ) 11/16"

Hope this helps, as you can, with a bit of mental arithmetic, cross reference Whitworth and AF gear.

George